Missouri Revised Statutes

105.030. Whenever any vacancy, caused in any manner or by any means
whatsoever, occurs or exists in any state or county office originally filled
by election of the people, other than in the offices of lieutenant governor,
state senator or representative, sheriff, or recorder of deeds in the city of
St. Louis, the vacancy shall be filled by appointment by the governor except
that when a vacancy occurs in the office of county assessor after a general
election at which a person other than the incumbent has been elected, the
person so elected shall be appointed to fill the remainder of the unexpired
term; and the person appointed after duly qualifying and entering upon the
discharge of his duties under the appointment shall continue in office until
the first Monday in January next following the first ensuing general
election, at which general election a person shall be elected to fill the
unexpired portion of the term, or for the ensuing regular term, as the case
may be, and the person so elected shall enter upon the discharge of the
duties of the office the first Monday in January next following his election,
except that when the term to be filled begins on any day other than the first
Monday in January, the appointee of the governor shall be entitled to hold
the office until such other date. This section shall not apply to vacancies
in county offices in any county which has adopted a charter for its own
government under section 18, article VI of the constitution. Any vacancy in
the office of recorder of deeds in the city of St. Louis shall be filled by
appointment by the mayor of that city.